Multi-source x-ray catheter

ABSTRACT

A multi-source x-ray/catheter delivers x-rays to a selected site within a body lumen. The x-ray sources are independently operable so that only the x-ray sources adjacent the target site generate x-rays during the procedure.

This application is a continuation application of U.S. Ser. No.09/709,661 filed Nov. 10, 2000 now U.S. Pat. No. 6,554,757, incorporatedherein by reference.

FIELD OF THE INVENTION

The invention relates to a multi-source x-ray catheter that selectivelygenerates x-rays to minimize adverse effects while maximizingtherapeutic effectiveness.

BACKGROUND AND SUMMARY OF THE INVENTION

Traditionally, x-rays have been used in the medical industry to viewbone, tissue and teeth. X-rays have also been used to treat cancerousand precancerous conditions by exposing a patient to x-rays using anexternal x-ray source. Treatment of cancer with x-rays presents manywell documented side effects, many of which are due to the broadexposure of the patient to the therapeutic x-rays.

Minimally invasive endoscopic techniques have been developed and areused to treat a variety of conditions. Endoluminal procedures areprocedures performed with an endoscope, a tubular device into the lumenof which may be inserted a variety of rigid or flexible tools to treator diagnose a patient's condition.

The desire for improved minimally invasive medical devices andtechniques have led to the development of miniaturized x-ray devicesthat may be used in the treatment or prevention of a variety of medicalconditions. International Publication No. WO 98/48899 discloses aminiature x-ray unit having an anode and cathode separated by a vacuumgap positioned inside a metal housing. The anode includes a base portionand a projecting portion. The x-ray unit is insulated and connected to acoaxial cable which, in turn, is connected to the power source. An x-raywindow surrounds the projecting portion of the anode and the cathode sothat the x-rays can exit the unit. The x-ray unit is sized forintra-vascular insertion, and may be used, inter alia, in vascularbrachytherapy of coronary arteries, particularly after balloonangioplasty.

International Publication No. WO 97/07740 discloses an x-ray catheterhaving a catheter shaft with an x-ray unit attached to the distal end ofthe catheter shaft. The x-ray unit comprises an anode and a cathodecoupled to an insulator to define a vacuum chamber. The x-ray unit iscoupled to a voltage source via a coaxial cable. The x-ray unit can havea diameter of less than 4 mm and a length of less than about 15 mm, andcan be used in conjunction with coronary angioplasty to preventrestenosis.

Miniaturized x-rays are not foolproof, however, and presentdifficulties. The x-ray unit generates heat, which can damage adjacenttissue. Additionally, x-rays are not localized and irradiate localtissue rather than only irradiating the desired site. Also, it isdifficult to maintain the positioning of these instruments inside at thedesired location. Improved miniaturized x-ray units the overcome thesedifficulties are desirable.

Other techniques are used to treat tumors with x-rays, includingplanting a seed of radioactive material at the tumor site, typicallyaccomplished with endoluminal procedures. However, the patient becomes“hot”, i.e., radioactive, and the procedure risks exposure of themedical personnel to radiation exposure.

As noted above, many types of cancerous and precancerous conditions aretreated by irradiating the tumor or site with x-rays. However, thex-rays are broadcast over a large area of healthy tissue in addition tothe tumor, since the radiation is administered from outside the body sothat it penetrates the skin and any internal organs or tissue to reachthe desired site. To avoid this, miniaturized x-ray systems whichgenerate x-rays at the desired site are a desirable alternative toconventional apparatus.

Many types of cancer occur in a body cavity or lumen, such as in therectum, vagina, esophagus or pulmonary passages. It is desirable totreat these cancers using miniaturized x-ray sources in combination withendoscopic techniques, which are minimally invasive to the patient, sothat the cancer or other intraluminal tissue is directly treated withx-rays.

The present invention overcomes the difficulties associated with x-raytherapy and apparatus of the prior art by providing an multi-sourcex-ray device that generates x-rays at the site of treatment andminimizes exposure of other tissues to irradiation.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-section of a preferred embodiment of a multi-sourcex-ray catheter according to the invention.

FIG. 2 is an alternative embodiment of multi-source x-ray catheter ofthe invention;

FIG. 3 is a cut-away view of a multi-source x-ray catheter of thepresent invention inside a body lumens;

FIGS. 4a and 4 b are an alternative embodiment having a hollow centrallumen with a balloon therein which inflates to push the x-ray sourcestowards the desired site; and

FIG. 5 is a detail of an x-ray source according to the invention.

DETAILED DESCRIPTION

FIG. 1 is a cross section of a preferred multi-source x-ray catheteraccording to the invention. Catheter 1 includes at least two x-raysources connected to a power supply by, e.g., a coaxial cable. The powersupply delivers sufficient energy to the x-ray source 2 to generatetherapeutically effective x-rays. Typically, voltages of from 10 to 60kilovolts (kV) are needed to generate the x-rays. X-ray sources 2 arelocated inside a lumen of x-ray shield 5 which is impenetrable to x-raysexcept at its distal end or, optionally, via transparent windows. Thex-ray sources are preferably evenly spaced about a circular catheterbody and are preferably independently operable, that is, they may beselectively turned on or off by the operator (see 2 a and 2 b). Thex-ray sources range from 1 to 15 mm in length and width. The overalldiameter of the device ranges from 10 to 100 mm.

Inner guide 6 is located in the center lumen of catheter 1 and issurrounded by x-ray shields. Additional lumens in the catheter maycontain a guide wire 7, circulation means 8, visual equipment 9, orother endoscopic tools as desired.

A preferred embodiment, shown in FIGS. 2 and 3 includes at least oneinflatable positioning balloon 20 adhered to the outer wall of the x-raytube. Positioning balloon 20 is inflated after proper positioning of theapparatus in the body lumen so that the position of the x-ray source ismaintained throughout treatment. Positioning balloon 20 may be adheredto the exterior wall of the x-ray tube by a suitable adhesive and isdesigned to bit inside catheter shields. This embodiment shows x-raysources in the on 2 a and off 2 b positions. It is preferred that aplurality of balloons are provided. Alternatively, a multi-chamberedballoon is provided to aid proper positioning of the apparatus in thebody lumen.

In a particularly preferred embodiment, a gas or liquid coolant ispassed through balloon 20 via tubes which communicate with both theinterior of positioning balloon 20 and a gas or liquid reservoir. Arespective circulation duct is provided for each balloon or balloonchamber so that they may be independently inflated. The positioningballoons 20 may be inflated with a gas or a liquid, but an x-rayabsorbent liquid is preferred. Normal saline is a particularly preferredliquid because it has a high heat capacity, is x-ray absorbent, and, inthe unlikely event of leakage, is compatible with the patient.

Optionally, a balloon 20 may be positioned in the center of the deviceas shown in FIG. 4 and inflated to push x-ray sources 2 outwardly in thedirection of the target tissue. In this embodiment, catheter body 1 andx-ray shield are made of flexible material, e.g., plastic, to expand orcontract with the inflation or deflation of the balloon.

Thermocouple 26 may be optionally affixed or placed in the vicinity ofthe x-ray source to measure temperature during the procedure.Thermocouple 26 may be in the form of a bimetallic strip and isoperatively connected to a temperature display device so that thetemperature is monitored during the procedure.

FIG. 3 shows an endoscope having an x-ray catheter according to theinvention positioned inside a body lumen. The device is positionedinside the lumen, and balloons 20 are inflated to position the catheternear the target site, in this case, a tumor. The x-ray sources 2 aadjacent to the tumor are turned on by the operator to generate x-rays,while the x-ray sources opposite the tumor remain in the off position 2b. The tumor is irradiated with the appropriate dose of x-rays, andwithdrawn from the body lumen.

FIG. 5 is a cutaway view of a typical x-ray source used in accordancewith the invention.

The present invention also relates to methods of treatment, prophylaxisand adjunctive therapy using the miniaturized x-ray apparatus of thepresent invention. Suitable for use with other endoscopic equipment, thex-ray device may be used to treat cancers of bodily lumens such ascolorectal cancer, vaginal cancer, esophageal cancer, pulmonary cancerssuch as lung cancers, stomach cancer, oral cancers, or any canceraccessible by a bodily lumen by positioning the device adjacent thetarget tissue and irradiating the tissue with a therapeuticallyeffective amount of x-rays. In similar fashion, one can treatpre-cancerous conditions or conditions related with cancer such asgastroesophageal reflux disease (GERD).

Although the present invention has been shown and described with respectto several preferred embodiments thereof, additional embodiments will beapparent to the skilled artisan without departing from the spirit andscope of the invention.

What is claimed is:
 1. An apparatus for delivering x-rays to a selectedsite within a body cavity comprising: an endoscope having a centrallumen; an x-ray shield which is impenetrable to x-rays positioned insaid central lumen, said x-ray shield being penetrable to x-rays at adistal end thereof; at least two x-ray sources positioned in respectivelumens of said x-ray shield, said x-ray sources being operably connectedto a power source and a multi-chambered positioning balloon on an outersurface of said endoscope.
 2. The apparatus of claim 1, furthercomprising a plurality of inflatable positioning balloons on the outersurface of said endoscope.
 3. The apparatus of claim 1, wherein saidendoscope has a visual lumen containing a visual device therein.
 4. Theapparatus of claim 1, further comprising a thermocouple affixed to theapparatus in the vicinity of the x-ray source.
 5. A method of treating acancerous or precancerous condition in a lumen of a patient comprising:inserting the apparatus of claim 1 into the lumen or a patient having acancerous or precancerous condition in a body lumen; positioning theapparatus proximate such that said at least two x-ray sources areproximate to the cancerous or precancerous condition; and irradiatingthe tumor with a therapeutically effective amount of x-ray radiationgenerated from at least one of the x-ray sources.
 6. A method oftreating a cancerous or precancerous tissue in a lumen of a patientcomprising: inserting the apparatus of claim 1 into the lumen of apatient having a cancerous or precancerous tumor in a lumen; positioningthe apparatus proximate such that said at least two x-ray sources areproximate to the cancerous or precancerous tumor; and irradiating thetumor with a therapeutically effective amount of x-ray radiationgenerated from at least one of the x-ray sources.
 7. A method oftreating a cancerous or precancerous tumor in a lumen of a patientcomprising: inserting the apparatus of claim 1 into the lumen of apatient having a cancerous or precancerous tumor in a lumen; positioningthe apparatus proximate such that said x-ray sources are proximate tothe cancerous or precancerous tumor; and irradiating the tumor with atherapeutically effective amount of x-ray radiation generated from atleast one of the x-ray sources.